The InnoDB write-ahead log ib_logfile0 is of fixed size,
specified by innodb_log_file_size. If the tail of the log
manages to overwrite the head (latest checkpoint) of the log,
crash recovery will be broken.

Let us clarify the messages about this, including adding
a message on the completion of a log checkpoint that notes
that the dangerous situation is over.

To reproduce the dangerous scenario, we will introduce the
debug injection label ib_log_checkpoint_avoid_hard, which will
avoid log checkpoints even harder than the previous
ib_log_checkpoint_avoid.

log_t::overwrite_warned: The first known dangerous log sequence number.
Set in log_close() and cleared in log_write_checkpoint_info(),
which will output a "Crash recovery was broken" message.

srv_shutdown(): Do not call log_free_check(), because it will now
be repeatedly called by ibuf_merge_all(). Do not call
srv_sync_log_buffer_in_background(), because we do not actually care
about durability during shutdown. Log writes will already be triggered
by buf_flush_page_cleaner() for writing back modified pages, possibly by
log_free_check().

logs_empty_and_mark_files_at_shutdown(): Clean up a condition.
This function is the caller of srv_shutdown(), and it will ensure that
the log and the buffer pool will be in clean state before shutdown.

mtr_t::release_page(): Remove. The function became unused in
commit 56f6dab1
when the call was replaced with a call to mtr_t::memo_release().

This is a backport of commit 8b6a308e
from MariaDB Server 10.6.11. No attempt to reproduce the hang
in earlier an earlier version of MariaDB Server than 10.6 was made.

In each caller of fseg_n_reserved_pages() except ibuf_init_at_db_start()
which is a special case for ibuf.index at database startup, we must hold
an index latch that prevents concurrent allocation or freeing of index
pages.

Any operation that allocates or free pages that belong to an index tree
must first acquire an index latch in non-shared mode, and while
holding that, acquire an index root page latch in non-shared mode.

btr_get_size(), btr_get_size_and_reserved(): Assert that a strong enough
index latch is being held.

dict_stats_update_transient_for_index(),
dict_stats_analyze_index(): Acquire a strong enough index latch.

These operations had followed the same order of acquiring latches in
every InnoDB version since the very beginning
(commit c533308a).

The hang was introduced in
commit 2e814d47 which imported
mysql/mysql-server@ac74632293bea967b352d1b472abedeeaa921b98
which failed to strengthen the locking requirements of the function
btr_get_size().

* MDEV-29397 Fix note turning into error

ODBC Rewind triggered an error with no SQL, but this is sometimes a
valid condition (as can be seen with other classes). Setting this to a 0
return stops errors firing when they shouldn't.

Also fixes ASAN hits from in MDEV-29687 tabext.cpp.

Let us avoid excessive allocation of explicit record locks.

spatial_index_info: Replaces index_tuple_info_t. Always take
a memory heap as a parameter to the member functions.
Remove pointer indirection for m_dtuple_vec.

spatial_index_info::add(): Duplicate any PRIMARY KEY fields that would
point to within ext->buf because that buffer will be allocated in
a shorter-lifetime memory heap.

Every operation that is going to write redo log is supposed to
invoke log_free_check() before acquiring any latches. If there
is a risk of log buffer overrun, a log checkpoint would be
triggered by that call.

ibuf_merge_space(), ibuf_merge_in_background(),
ibuf_delete_for_discarded_space(): Invoke log_free_check()
when the current thread is not holding any page latches.

Unfortunately, in lower-level code called from ibuf_insert()
or ibuf_merge_or_delete_for_page(), some page latches may be
held and a call to log_free_check() could hang.

ibuf_set_bitmap_for_bulk_load(): Use the caller's mini-transaction.
The caller should have invoked log_free_check() while not holding
any page latches.

Something appears to be broken in the DBUG subsystem.
Let us remove frequent calls to it from the InnoDB internal SQL interpreter
that is used in the purge of transaction history.

The DBUG_PRINT in que_eval_sql() can remain for now, because those
operations are much less frequent.

This fixes up commit e3c39c0b

InnoDB crash recovery can run out of memory before
commit 50324ce6 in
MariaDB Server 10.5.

Let us disable some frequently failing recovery tests
in earlier versions.

Not creating explicit record locks will speed up the test.

Also, disable the use of InnoDB persistent statistics in the test of
MDEV-27270 to avoid intermittent failures in 10.6 or later
(after commit 9608773f)
due to the nondeterministic scheduling of STATS_AUTO_PERSISTENT.

The file plugin_exports became unused in
commit fec844ac

- mariabackup fails to assign srv_undo_space_id_start when the
dedicated undo tablespaces are disabled

Problem:-
  We are able to insert duplicate value in table because cmp_binary_offset
  is not able to differentiate between NULL and empty string. So
  check_duplicate_long_entry_key is never called and we don't check for
  duplicate.
Solution
  Added a if condition with is_null() on field which can differentiate
  between NULL and empty string.

When trying to output stacktrace, and addr2line is not installed, the
child process forked by start_addr2line_fork() will fail to do exec(),
and finish with exit(1).

There is a problem with exit() though - it runs exit handlers,
and for the forked copy of crashing process, it is a bad idea.

In 10.5+ code for example, exit handlers include
tpool::task_group static destructors, and it will hang infinitely
waiting for completion of the outstanding tasks.

The fix is to use _exit() instead, which skips the execution of exit
handlers

Make sure that EXPLAIN object allocated on runtime arena.

MDEV-29924 Assertion `(((nr) % (1LL << 24)) % (int) log_10_int[6 - dec]) == 0' failed in my_time_packed_to_binary on SELECT when using TIME field

when assigning the cached item to the Item_cache for the first time
make sure to use Item_cache::setup(), not Item_cache::store().
Because the former copies the metadata (and allocates memory, in case
of Item_cache_row), and Item_cache::decimal must be set for
comparisons to work correctly.